Push-button switch with conductive coil spring contact

ABSTRACT

A push-button switch comprises a substrate, supporting thereon an electric circuit, and a slider lever. The slider lever carries a conductive coil spring which functions as a moving contact which will open and close the electric circuit as the slider lever moves relative to the substrate.

United States. Patent [191 Murata [11] 3,823,292 July 9,1974

[ PUSH-BUTTON SWITCH WITH CONDUCTIVE COIL SPRING CONTACT [75] Inventor: Taneo Murata, Tokyo, Japan [73] Assignee: Alps Electric Co., Ltd., Tokyo,

Japan [22] Filed: Mar. 16, 1973 [21] Appl. No.: 341,866

[30] Foreign Application Priority Data Mar. 17, 1972 Japan 47-32197 [52] US. Cl 200/159 R, 200/166 BA [51] Int. Cl. H0lh 1/06, HOlh 13/12 [58] Field of Search 200/159 R, 166 BA, 16 D [56] References Cited UNITED STATES PATENTS 1,873,141 8/1932 Norviel et al 200/166 BA UX 2,025,981 12/1935 Getty 200/166 BA UX 2,882,514 4/1959 Krantz 200/166 BA UX 3,493,705 2/1970 Noll et al. 200/159 R 3,674,953 7/1972 Brevick ZOO/l6 D X Primary ExaminerRobert K. Schaefer Assistant Examiner-William J Smith Attorney, Agent, or Firm-Eliot S. Gerber, Esq.

[57] ABSTRACT A push-button switch comprises a substrate, supporting thereon an electric circuit, and a slider lever. The slider lever carries a conductive coil spring which functions as a moving contact which will open and 7 close the electric circuit as the slider lever moves relative to the substrate.

4 4 Claims, 5 Drawing Figures PATENTED JUL 91974 FIG. 2

PUSH-BUTTON SWITCH WITH CONDUCTIVE COIL SPRING CONTACT BACKGROUND OF THE INVENTION This invention relates to a push-button Switch and, more particularly, to improvement of thetype of pushbutton switch in which a conductive coil spring functions as the moving contact.

Push-button switches are widely used for electrical controls, for example to temporarily make an electrical circuit in a toy or appliance. But many push-button switches are too inexpensively made to operate reli- 7 SUMMARY OF THE INVENTION According tothe present invention a novel pushbutton switch is provided which comprises a substrate supporting thereon an electric circuit. A slider lever carries a conductive coil spring which functions as a moving contact. The spring will open and close the electric circuit as the slider lever moves relative to the substrate in response to externally applied forces, such as hand motion.

Specifically, the coil spring is disposed in an open cavity formed in the slider lever. The opposing wall faces of the slider lever, upon which the axial ends of the coil spring abut, are tapered and diverge outward, so that the coil spring assumes (in an unconfined state) a fan-like in side view. A recess is formed in a bottom face of the open cavity permitting flexing of the center portion of the coil spring, so that the coil spring comesto contact with the electric circuit smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross sectional view of an embodiment of the push-button switch according to the present invention; V j FIG. 2 is a view similar to FIG. 1 where the switch is turned about 90 from the position shown in FIG. 1;

FIG. 3 is an enlarged schematic sectional view showing the relation between a substrate and a coil spring disposed in an open cavity;

FIG. 4 is a view similar to FIG. 3 where the substrate has some unevenness; and

F IG. 5 is an enlarged schematic sectional view showing the unconfined state of the coil spring disposed in the open cavity.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 through 5, an embodiment of the push-button switch according to the present invention includes a push-button head 1 with a projection 4 made of, for example, molded synthetic plastic resin. The push-button head 1 is formed in its rear face 2 with an annular groove 3 which receives one end of a coil scribed later.- Th projection 4, provided integrally on the rear face 2 of the push-button head 1, supports fixedly (or is coupled to) a slider lever 5, so that the push-button head I and theslider lever 5 move together as a pushing force is applied to the head. It should be' understood that, although the embodiment includes the separate slider lever 5, the lever 5 can be manufactured integral with the projection 4 and/or'the head 1.

The slider lever 5 is formed with an open cavity 6, as shown in FIG. 1, for accommodating a coil spring 11. The coil spring 11 functions as the movable contact of the switch. Opposing wall faces 7 and 7 of the open cavity 6 upon which the axial ends of the coil spring 11 abut, when the spring is disposed in the cavity, are tapered so as to diverge outward. A recess 9 is formed in a bottom face 8 of the open cavity 1 l, as shown in FIG. 3. The'slider lever 5 has stopper portions (shoulders) 10 and 10 as shown in FIG. 2.

. The coil spring 11, which'functions as-a moving 7 contact, is preferably made of goodelectrically conductive material such as gold or silver, or from aconductive spring coil coated with good conductive material such as gold or silver.

The coil spring 11 is dimensioned in relation to the open cavity 6 in which it is disposed so that the axial length of the coil spring is a little: longer than the distance between the tapered opposing wall faces 7 and 7 of theopen cavity. The diameter of each spring coil is sized so as to jut a little out of the open cavity 6, as

shown in FIG; 3. The jutting portions of the coil spring 11 may contact an electric circuit (not shown) provided on a substrate 12 and will produce an open/close state in the electric circuit as the push-button head 1 is which a hole 15 is formed in the bottom of the frame spring 18 fornormal reversion of the head 1, as de- 13. The frame 13 is further formed with a hollow (cavity) 14 permitting sliding ofv the: slider lever 5, and grooves (not shown)for guiding the lever 5 while :it moves into'and out of the hollow 4. 1

A top plate 16, for example also made of molded synthetic plastic resin, is mounted on the open top of the frame 13 as shown in FIG. 1 and fixed by appropriate fixing elements to the frame 13. The top plate 16 serves as a limiter for thestopper portions 10 and 10 of the lever 5 and is formed with a hole 17 through which the lever 5 slidingly moves.

The coil spring 18, for reversion (normal return) of the head I, with its lever 5, is disposed between the rear face 2 of the head 1 and the top plate 16, as shown in FIG. 1.

In assembling the afore-described switch elements, first, the substrate. 12 (formed previously with its printed electric circuit) is secured in the frame 13 through the hole 15 formed in such a relation that the electric circuit formed on the substrate 12 faces the center of the hollow 14. Then, the coil spring 11, functioning as a moving contact, is disposed in the open cavity .6 formed in the slider lever 5. As a result, because the opposing wall faces 7 and 7 of the open cavity 6 are tapered and diverging outward in the moving direction of the slider lever 5, the coil spring 11 is forced to assume a fan-like shape in side view, as shown in FIG. 5. v

Then, the lever with the coil spring 11 is inserted in the hollow 14 formed in the switch frame 13 so that the coil spring 11 comes into contact with the substrate 12 and the electric circuit provided thereon.

The top plate 16 is put on the open top of the frame 13 and fixed by appropriate fixing elements, for example heat or glue or metal tabs, then, the push-button head 1 with its projection 4 is coupled and fixed to the slider lever 5 while interposing the reversion coil spring 18 between the rear face 2 of the head 1 and top plate 16, thereby completing the push-button switch. The frame 13 may be round i.e., tubular or square or of other shapes.

As described hereinabove, the present invention provides the novel structure of the push-button switch wherein the opposing wall faces 7 and 7 of the open cavity 6 formed in the slider lever 5 accommodate the conductive coil spring 11. Those wall faces are tapered and diverge outwardly in the moving direction of the slider lever 5. The recess 9 is formed in the bottom face 8 of the open cavity 6, so that when the slider lever 5, with the coil spring 11, is assembled with the switch frame 13, the height section of the fan-shaped coil spring 11 abuts first upon the substrate 12 and, then adjacent coil sections of the coil spring 11 come progressively into contact with the substrate 12. At the same time the height section of the coil spring sinks into the recess 9, to permit free flexion of the height section, resulting in an easy insertion operation of the lever 5 without damaging the coil spring 11.

Further, as shown clearly in FIG. 3, the axial end portions of the fan-shaped coil spring 11 are crowded while the height or center section of the same is coarse i.e., uncrowded. The end portions of the coil spring may contact strongly with portions of the substrate 12, where no electric circuit is formed, whereas the height (center) section will contact smoothly with the electric circuit, resulting in a good contact condition, whereby low-noise, low-cost, push-button switches of long lifetimes can be manufactured.

Furthermore, since the coil spring 11 is forced to assume a fan-like shape in side view, the coil elements of the coil spring 11 do not accumulate in one point, this being one of the advantages from the practical point of view. In addition, since the coil spring 11 is generally coarse i.e., uncrowded and unbunched, the moving contact of the conductive coil spring 11 exhibits good resiliency even when the substrate 12 has some unevenness, as shown in FIG. 4.

I claim:

1. A push-button switch comprising a substrate supporting thereon an electric circuit, a slider lever supported slidably relative to said substrate, and a conductive coil spring functioning as a moving contact disposed in an open cavity formed in said slider lever and adapted to come into contact slidably with said substrate to open and close said electric circuit as said slider lever moves relative to said substrate, wherein the opposing wall faces of said open cavity upon which the axial ends of said coil spring abut are tapered and diverge outwardly so that said coilspring assumes a fan-like shape in side view in an unconfined state, and

said open cavity is formed with a recess in the bottom face thereof so that the center portion of said coil spring can flex.

2. A push-button switch as set forth in claim 1 wherein said open cavity is dimensioned relative to said coil spring so that the distance between said opposing wall faces is a little shorter than the length of said coil spring uncompressed, and the depth of said open cavity is a little shorter than the diameter of said spring coils.

3. A push-button switch as set forth in claim 2 wherein said coil spring is made of an electrically good conductive metal.

4. A push-button switch as set forth in claim 2 wherein said coil spring is made from a conductive metal coil coated with a different metal of superior electrical conductivity. 

1. A push-button switch comprising a substrate supporting thereon an electric circuit, a slider lever supported slidably relative to said substrate, and a conductive coil spring functioning as a moving contact disposed in an open cavity formed in said slider lever and adapted to come into contact slidably with said substrate to open and close said electric circuit as said slider lever moves relative to said substrate, wherein the opposing wall faces of said open cavity upon which the axial ends of said coil spring abut are tapered and diverge outwardly so that said coil spring assumes a fan-like shape in side view in an unconfined state, and said open cavity is formed with a recess in the bottom face thereof so that the center portion of said coil spring can flex.
 2. A push-button switch as set forth in claim 1 wherein said open cavity is dimensioned relative to said coil spring so that the distance between said opposing wall faces is a little shorter than the length of said coil spring uncompressed, and the depth of said open cavity is a little shorter than the diameter of said spring coils.
 3. A push-button switch as set forth in claim 2 wherein said coil spring is made of an electrically good conductive metal.
 4. A push-button switch as set forth in claim 2 wherein said coil spring is made from a conductive metal coil coated with a different metal of superior electrical conductivity. 